Hey all, Wanted to share my research on DEF faults for my truck in hopes to help others.
I replied in another thread but wanted to start a new one. This gets long.

To make it short I have had 3 instances of DEF faults. 1st they did a TSB, second the nox sensor had to be replaced, and third the nox sensor went out of tolerance on temperature.

After all of these faults I want to get to the bottom of it. Ford engineer blamed it on bad fuel and said to clean carbon out of EGR and bill customer for it. If you guys dont know I am very big into the fuel business so I had the diesel tested. Ford engineer said cetane needed to be above 40. Test results of my fuel was 46. Ford engineer said the bad fuel causes carbon buildup in EGR. BP lead chemist said there is no way the cetane number will cause carbon build up. It is an air to fuel ratio thats off causing carbon build up.

Dealer called an automotive chemical company to come look at truck. I forget the name of it and I am trying to keep this short. The chemical engineer agreed with BP and said the fuel doesnt cause it and he agreed running the additive in fuel was a waste of money. Too much additive will cause a DEF fault as well triggering NOX sensor.
My truck has 16,000 miles on it and they decided to do a EGR system clean on it. On a scale of 1 to 10, it was at a level 5. I was shocked and we have sent that into ford waiting for a reply back. Beofre we did the clean, temp going in was 1200 and coming out was 900 degrees. After clean temp coming out was 600 so it is obvious it had some carbon in it.
Chemist that did this to the truck did say city driving doesnt hurt them but to go on highway every once in a while.
WE THINK and are pretty positive......the truck is getting carbon in EGR cooler causing faults is because I do idle and he did say that these high fuel pressure motors "coke up" the worst when idling. He did say to quit it at all necessary. He said to idle a little bit after highway hauling but other than that not to do it. There is alot more to this but kept that facts straight and short for everyone. I will advise as we go further on this.

So far my truck is doing great and I am pursuing on to get answers.

 

Thanks for the very informative post. You have some great resources available to you.
I guess you’ll know if idling is truly the issue if you can significantly reduce that.

As far as shutting down immediately, did you hear any concern from them about the turbo?
For example, after I park my turbo goes through a few spin cycles over a 20-30 second period which I tend to wait for.
It will spool up, partially spool down, spool back up and then spool down completely as if it was giving a big sigh of relief.
Sometimes I time it wrong and shut down right as it’s spinning up during that last cycle.

This is interesting. Please keep us updated.

 

The only talk we talked about turbo was of course after hauling down the highway for a long time and it gets good and hot. After you stop then let it idle for a minute to get the EGT's down for turbos sake. It doesnt take long to get the EGT's down. My truck has that little bit of turbo whine but we are not concerned about it too much right now. My truck runs great and Ford says its normal. I dont think it is but I have alot of warranty left.

Other than going down the highway for an extended period of time, he said to shut it off ASAP when you get done to avoid idling.

 

Where was the DEF from when you filled it up or topped it off last?

 

Blue Def is all I use. Buy it from one of my BP stores.

We talked about def level sensors but that was quickly ruled out. This last DEF fault was an out of tolerance temp from NOX sensor and then went away. We were able to get a code though.

We do know DEF or that tank sensors have nothing to do with this.

 

When pulling and especially on the hwy for extended time let that thing idle for about 5 minutes. If you have been running the tank out from fillup to fillup don't even shut it down during fueling.

Many a time the EGTS take quite awhile to truly come down because of residual heat.

don't let your turbo bearings run dry and cook the oil.

High idle it if you have to idle a lot and that may help with the egr and its operation.

 

In the summer it does take a minute or two for temps to drop even around town.
I shut down when EGT1 is under 400°F.

When I idle on purpose, it's with SEIC.
I've never had an issue or even the drive to clean message and it's my daily driver.
I don't usually high idle during refueling though and of course drive thru's are normal idle.

 

I did the high idle to my 6.0 but this 6.7 seems very complicated to do.

I forgot to add that my dealer is going to start offering this egr clean. It will be 130 dollars. It sounds like it would be beneficial once a year. I am taking the position though that the truck should not build up carbon in the egr cooler and ford needs to fix it. That's where we are at right now and I will be reporting in on what they say.

 

Could go the route of deleting and not even have to worry about it!

 

Every egr system gets carbon. That's why its called exhaust gas recirculation. One cure. Delete.

 

SEIC is easy.
Select the correct resistor for the RPM you want and wire the PCM wire to the resistor to an upfitter switch wire and you're done.
Most difficult part is finding the correct color PCM wire.
Put in park, set the e-brake, flip the switch and let it idle.

I am curious what my number would be on buildup but again, haven't had the issue in 50 something thousand miles.

 

I don't have up fitters on mine

If there were easier instructions I would do it. Miss it when I had it on my 6.0

 

I had to add the upfitter fuse box and switches to mine, also something that's easy to do.
I had to use the 2008 6.4L book but here is a link to the 2011 installation.

https://www.fleet.ford.com/truckbbas...tml/Q157R2.pdf

I also attached a PDF of what I did back in 2010.
Not perfect but it's what I figured out.

 

You know something just occurred to me. Doesn't the egr valve only open when the motor is up in rpm's?

If that's the case then it may be impossible for that egr cooler to get carbon in it from idling.

 

Every EGR that I know of cycles at idle.